Denis is available for hire
Hire DenisDenis Andros
Verified Expert in Engineering
Mobile Developer
Kraków, Poland
Toptal member since November 8, 2021
Bio
Denis is a software developer with 12+ years of experience in Android and iOS mobile native development and architecture. He is an expert in Kotlin, Java, Swift, Objective-C, .NET, and C++. With solid technical and communication skills, Denis easily solves technical leadership challenges and provides guidance to development teams.
Portfolio
HungerStation LLC - Main
Android, Kotlin, Flutter, Android Jetpack, Jetpack Compose, Android SDK...
TrustArc Inc
Kotlin, Java, Swift, iOS, Android, Android SDK, SDKs, Flutter, Dart, Plugins
ShiftKey, LLC
Android, Kotlin, Android SDK, Android Jetpack, Android Studio, Coroutines...
Experience
- Android - 12 years
- iOS - 8 years
- Kotlin - 8 years
- Mobile Development - 8 years
- Swift - 7 years
- .NET - 7 years
- Bluetooth Low Energy (LE) - 2 years
Work Experience
Android Developer
2024 - 2026
HungerStation LLC - Main
- Built the end-to-end Pickup ordering journey, including map discovery, store selection, scheduled orders, checkout pickup integration, and QC pickup entry points.
- Integrated Google Maps and Huawei Map Kit engines for Pickup map clustering, improving merchant discovery, and map performance in dense areas. Delivered monetization and engagement initiatives, including Coupon Packs subscription.
- Reduced Pickup TTI from around 2 seconds to under 1 second through profiling, rendering optimization, and architecture-level performance improvements.
- Accelerated mobile modernization with Jetpack Compose modules, Flutter-based cross-platform checkout/menu features, and KMP experimentation-driven feature delivery.
- Built and integrated AI-assisted engineering workflows and Claude/Cursor skills into the SDLC, supporting feature development, refactoring, code review, and technical documentation.
Technologies: Android, Kotlin, Flutter, Android Jetpack, Jetpack Compose, Android SDK, Kotlin Multiplatform, iOS, Swift, SwiftUI, Claude Code, Agentic AI, AI-assisted Development, AI Tools, AI Programming, Kotlin Multiplatform Mobile (KMM)
Android and iOS Developer
2023 - 2024
TrustArc Inc
- Integrated the IAB’s Transparency and Consent Framework (TCF) v2.2 into mobile consent management SDK for Android and iOS.
- Integrated the Google consent mode into mobile consent management SDK for Android and iOS.
- Implemented a Flutter plugin (supports iOS and Android) for consent management SDK.
Technologies: Kotlin, Java, Swift, iOS, Android, Android SDK, SDKs, Flutter, Dart, Plugins
Senior Android Engineer
2021 - 2023
ShiftKey, LLC
- Advanced a healthcare scheduling app, creating an easy-to-maintain and scalable tool for healthcare workers.
- Delivered the major features of the application with Kotlin and Jetpack Compose.
- Developed custom Jetpack Compose user interface components.
- Implemented a pixel-perfect UI using Figma, Android Jetpack Compose, and other native Jetpack components.
Technologies: Android, Kotlin, Android SDK, Android Jetpack, Android Studio, Coroutines, Jetpack Compose
Senior Android iOS Developer
2019 - 2022
Rider
- Built an Android application that unifies a network of stores of goods for extreme sports such as snowboarding, skiing, cross-country skiing, etc. The app is available here: play.google.com/store/apps/details?id=com.rider.promo.
- Developed the iOS version of the same application for the App Store (https://apps.apple.com/by/app/%D1%80%D0%B0%D0%B9%D0%B4%D0%B5%D1%80/id1321797151).
- Architected eCommerce applications that manage discounts, promos, and news.
Technologies: Android, Android Studio, Kotlin, KOIN, Firebase, iOS, Xcode, CocoaPods, Firebase Cloud Messaging (FCM), Firebase Cloud Functions, Firebase Authentication, Firebase Analytics, Firebase Realtime Database
Android Tech Lead | Developer
2021 - 2021
NDA
- Developed the patient services mobile app for a pharmaceutical company, including medication tracking and reminders, disease activity trends, charts and reports, patient adherence tracking, and education content media library.
- Built the system architecture, created solution designs, performed team technical leadership, and developed the application.
- Supported offline content management, integrated with the Salesforce SDKs—SmartSync and SmartStore.
Technologies: Android, Kotlin, KOIN, Salesforce
iOS Tech Lead | Developer
2019 - 2021
Imperial Tobacco
- Developed the enterprise app suite for iPad to help sales representatives with the in-field sales solutions integrated with Salesforce: product orders, route planning, warehouse and stock management, and customer and outlet management or assessment.
- Led a technical team and developed the application, system architecture, and solution designs.
- Integrated with the Salesforce SDKs, specifically with SmartSync and SmartStore, and maintained offline content management.
Technologies: iOS, Swift, Objective-C, Salesforce, Core Data, AVKit
iOS and Android Technical Lead | Architect
2018 - 2019
NDA
- Developed an enterprise passwordless authentication solution for iOS and Android that allows individuals to authenticate into workstations—macOS, Win, Linux—and other sensing assets simply by being close to it.
- Created the secured Bluetooth communication, emulated PIV card, and optimized the device battery usage.
- Created the system architecture and solution designs, managed a team of technical experts, and oversaw the application development.
Technologies: Android, iOS, Kotlin, Swift, Bluetooth Low Energy (LE)
iOS and Android Technical Lead | Developer
2015 - 2018
Anytime Fitness
- Developed the Anytime Fitness and personal trainer applications for Android and iOS.
- Migrated the codebase from Objective-C and Java to Swift and Kotlin.
- Implemented various features such as training workouts, chat, and calendars.
- Developed the solution designs, acted as the technical team leader, and managed the application development.
Technologies: iOS, Android, Swift, Kotlin, Objective-C, Java, .NET, Firebase
Mobile Developer
2012 - 2015
Coherent Solutions
- Developed healthcare plans and Benefits of WEX for Android/iOS applications.
- Proposed, designed, and developed applications architecture.
- Developed major application features such as biometric login/barcode scanner.
- Developed and instrumented CI with integration tests.
- Worked on various tasks, as needed, including caching, fixing bugs, making improvements (UI, memory, code), sending tracking data, and writing tests.
Technologies: Android, Java, iOS, Objective-C
C/C++ .NET Developer
2009 - 2012
Coherent Solutions
- Developed a .NET-based framework developed to substitute legacy DCOM-based transport used in the data engine. Xenon Computing Platform (TMxe) provides a TCP message transport between applications and servers.
- Created server and client-side proxy components and allowed the client application to operate with the data in the relational database as a set of COM objects within the given object model. Data Engine is a COM-based data management platform.
- Performed Oracle and MS SQL Server support for Data Engine via OLE DB.
- Designed and implemented thread pool-based message processing under system heavy load.
- Improved platform performance and stability, like memory consumption and deadlocks.
Technologies: C++, C#, C#.NET, .NET, Transmission Control Protocol (TCP), TCP/IP, Networking, Oracle, Microsoft SQL Server, OLE DB
C/C++/.NET Developer
2006 - 2012
Coherent Solutions
- Worked on employee time management systems that reduce labor costs through automated scheduling, recording, reporting, and controlling work schedules.
- Designed and developed GUI and ActiveX components.
- Performed Oracle/MS SQL support for data engine via OLE DB.
- Created the universal COM object accessor as interop for JavaScript engine.
- Developed the ESR platform, a web-based HR enterprise system.
Technologies: C++, Microsoft Foundation Classes (MFC), Microsoft Foundation Class (MFC) Library, ATL, COM, Win32 API, ActiveX, .NET, C#, C#.NET, ASP.NET MVC, JavaScript, HTML, CSS, OLE DB
C/C++ Developer
2004 - 2006
Coherent Solutions
- Worked for John Deere: Field Doc, an American manufacturer of agricultural, construction, and forestry machinery.
- Developed applications executed under the VxWorks operating system. The applications help to manage the controllers installed on agricultural vehicles.
- Designed and implemented the GPS decode module component.
- Implemented the flag module component. Identified and fixed existing system bugs.
Technologies: C, C++, VxWorks, Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC), Win32 API, CAN Bus, RS-232, GPS, A-GPS
Project History
Hungerstation Mobile App
https://hungerstation.com/Contributed to a high-scale food delivery platform with 20+ million downloads, a multi-million weekly active mobile user base, and a 4.3 rating across 340,000+ reviews, delivering performance-critical Android / Cross-platform experiences across pickup, checkout, and growth flows.
Built the end-to-end Pickup ordering journey, including map discovery, store selection, scheduled orders, and checkout pickup integration.
Integrated Google Maps and Huawei Map Kit engines for Pickup map clustering, improving merchant discovery, and map performance in dense areas.
Reduced Pickup TTI from around 2 seconds to under 1 second through profiling, rendering optimization, and architecture-level performance improvements.
Accelerated mobile modernization with Jetpack Compose modules, cross-
platform checkout/menu features, and experimentation-driven feature delivery.
Built the end-to-end Pickup ordering journey, including map discovery, store selection, scheduled orders, and checkout pickup integration.
Integrated Google Maps and Huawei Map Kit engines for Pickup map clustering, improving merchant discovery, and map performance in dense areas.
Reduced Pickup TTI from around 2 seconds to under 1 second through profiling, rendering optimization, and architecture-level performance improvements.
Accelerated mobile modernization with Jetpack Compose modules, cross-
platform checkout/menu features, and experimentation-driven feature delivery.
ShiftKey Android / iOS Applications
https://www.shiftkey.com/ShiftKey platform helps nursing, therapy, and dental professionals to find & work shifts. I was involved in mobile app architecture & major features development.
https://play.google.com/store/apps/dev?id=8426692984949227741&hl=en_US&gl=US
https://apps.apple.com/us/app/shiftkey-prn-healthcare-jobs/id1532097671
• Advanced a healthcare scheduling app, creating an easy-to-maintain and scalable tool for healthcare workers.
• Delivered the major features of the application with Kotlin and Jetpack Compose.
• Developed custom Jetpack Compose user interface components.
Implemented a pixel-perfect UI using Figma, Android Jetpack Compose, and other native Jetpack components.
• Integrated Lottie animations
• Implemented Geofecing / Digital Invoicing app features
https://play.google.com/store/apps/dev?id=8426692984949227741&hl=en_US&gl=US
https://apps.apple.com/us/app/shiftkey-prn-healthcare-jobs/id1532097671
• Advanced a healthcare scheduling app, creating an easy-to-maintain and scalable tool for healthcare workers.
• Delivered the major features of the application with Kotlin and Jetpack Compose.
• Developed custom Jetpack Compose user interface components.
Implemented a pixel-perfect UI using Figma, Android Jetpack Compose, and other native Jetpack components.
• Integrated Lottie animations
• Implemented Geofecing / Digital Invoicing app features
Anytime Fitness, Anytime Workouts (Android/iOS Applications)
https://www.anytimefitness.com/Developed the Anytime Fitness and Personal Trainer applications for Android and iOS.
• Successfully migrated the existing codebase from Objective-C and Java to Swift and Kotlin, enhancing overall performance and maintainability.
• Pioneered the implementation of a multitude of features, including training workout functionality, real-time chat functionality, and integrated calendar capabilities.
• Drove the solution design process, assuming the role of technical team leader and effectively coordinating the application development efforts.
FEATURES IMPLEMENTED
• Access to over 1,000 workouts
• Communication with a coach or personal trainer; tracking progress
• Finding gym locations and contact information
• Club offers and promotions
• Scheduling, viewing, confirming, and canceling appointments
• Successfully migrated the existing codebase from Objective-C and Java to Swift and Kotlin, enhancing overall performance and maintainability.
• Pioneered the implementation of a multitude of features, including training workout functionality, real-time chat functionality, and integrated calendar capabilities.
• Drove the solution design process, assuming the role of technical team leader and effectively coordinating the application development efforts.
FEATURES IMPLEMENTED
• Access to over 1,000 workouts
• Communication with a coach or personal trainer; tracking progress
• Finding gym locations and contact information
• Club offers and promotions
• Scheduling, viewing, confirming, and canceling appointments
Education
1997 - 2002
Bachelor's Degree in Artificial Intelligence
Belarusian State University of Informatics and Radioelectronics - Minsk, Belarus
Skills
Libraries/APIs
REST APIs, Microsoft Foundation Class (MFC) Library, Win32 API, ATL, AVKit, Microsoft Foundation Classes (MFC), CocoaPods
Tools
Android Studio, Xcode, AppCode, Git, Android Jetpack, DJI SDK, Firebase Cloud Messaging (FCM), Firebase Authentication, Firebase Analytics, Claude Code
Languages
Kotlin, Swift, Java, Objective-C, JavaScript, C++, C, C#, C#.NET, HTML, CSS, GraphQL, Dart
Frameworks
Android SDK, .NET, Core Data, KOIN, ActiveX, ASP.NET MVC, Flutter, SwiftUI
Paradigms
Mobile Development
Platforms
Android, iOS, Bluetooth Low Energy (LE), Salesforce, Firebase, VxWorks, Oracle
Storage
Microsoft SQL Server, Firebase Realtime Database
Other
Coroutines, Jetpack Compose, Mobile Apps, SDKs, Mapbox SDK, Kotlin Multiplatform, Kotlin Multiplatform Mobile (KMM), Software Development, Systems Engineering, Lottie, Geofencing, CAN Bus, RS-232, COM, OLE DB, Transmission Control Protocol (TCP), TCP/IP, Networking, GPS, A-GPS, Firebase Cloud Functions, Plugins, Agentic AI, AI-assisted Development, AI Tools, AI Programming
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